Communication systems typically include a plurality of communication units, such as mobile or portable radio units and dispatch consoles that are geographically distributed among various repeater sites and console sites. The communication units wirelessly communicate with the repeater sites and each other, and are often logically divided into various subgroups or talkgroups. Communication systems may be organized as trunked systems, where a plurality of communication resources is allocated amongst multiple users or groups by assigning the repeaters within a radio frequency (RF) coverage area on a call-by-call basis, or as conventional (non-trunked) radio systems where communication resources are dedicated to one or more users or groups. In trunked systems, or in mixed trunked and conventional systems, there is usually provided a central controller (sometimes called a “zone controller”) for allocating communication resources among multiple sites. The central controller may reside within a single device or multiple devices and may be located at a fixed equipment site or may be distributed among the repeater or console sites.
Traditionally, the repeater and console sites were linked via a circuit-switched architecture, through dedicated or on-demand circuits to a central radio system switching point (“central switch”). The circuits providing connectivity to the central switch required a dedicated wire for each endpoint (e.g., repeater site or console site) whether or not the endpoint was participating in a particular call. Often, the bandwidth (circuits) between endpoints were pre-provisioned for certain types of calls, for example for trunked calls and/or conventional calls. If a circuit was available for a trunking call, the zone controller reserved the circuit and granted the call. Otherwise, if a circuit was unavailable, the zone controller busied the call until such time as resources became available. For conventional calls, circuits were pre-allocated from the conventional channels to the central switch.
More recently, communication systems are using packet-switched networks where information that is to be communicated between endpoints is divided into packets and transported by various routers forming an Internet Protocol (IP) network. For example, communication systems using packet-switched networks are described and claimed in U.S. Pat. No. 6,141,347, titled “Wireless Communication System Incorporating Multicast Addressing and Method for Use” and U.S. patent application Ser. No. 09/464,269, titled “Methods for Implementing a Talkgroup Call in a Multicast IP Network,” each of which is assigned to the assignee of the present invention and incorporated herein by reference in its entirety.
Packet-switched networks are sometimes called “connectionless” networks because they do not provide dedicated bandwidth or circuits between endpoints, but rather permit communications between multiple endpoints to proceed concurrently over shared paths or connections. U.S. patent application Ser. No. 09/728,621, titled “Method for Managing Bandwidth in a Packet-Based Communication System, assigned to the assignee of the present invention and incorporated herein by reference in its entirety, discloses and claims a method of call control in a packet-based network that allocates “call counts,” or call units of bandwidth eligible for use on certain paths, such that calls may be established without exceeding available bandwidth. The present application discloses and claims a reservation-based method of determining call counts that may be utilized by zone controllers or other host devices of a communication network.